I had some problems at first, notably that removal was a huge pain (literally) and that the stem kept stabbing me. I had to open the cup's holes with a large needle and trim off almost all of the stem. When I was reaching for the stem all the time, I kept stabbing myself with my fingernails and generally having a miserable time. I keep my nails really short (no growth past the fingertips) so I couldn't trim them back anymore. I've found that since I've stopped relying on the stem at all, it's been easier to remove and use my cup.
After not having much success with hooking my finger over the rim, I experimented with squeezing the base to release the suction. That worked really well! It's also easier to grab the whole bottom of the cup to rotate it, ensuring suction, than to try and twist it by the stem.